2 * mm/rmap.c - physical to virtual reverse mappings
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL).
7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible.
10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode.
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004
21 * Lock ordering in mm:
23 * inode->i_mutex (while writing or truncating, not reading or faulting)
26 * When a page fault occurs in writing from user to file, down_read
27 * of mmap_sem nests within i_mutex; in sys_msync, i_mutex nests within
28 * down_read of mmap_sem; i_mutex and down_write of mmap_sem are never
29 * taken together; in truncation, i_mutex is taken outermost.
32 * page->flags PG_locked (lock_page)
33 * mapping->i_mmap_lock
35 * mm->page_table_lock or pte_lock
36 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
37 * swap_lock (in swap_duplicate, swap_info_get)
38 * mmlist_lock (in mmput, drain_mmlist and others)
39 * mapping->private_lock (in __set_page_dirty_buffers)
40 * inode_lock (in set_page_dirty's __mark_inode_dirty)
41 * sb_lock (within inode_lock in fs/fs-writeback.c)
42 * mapping->tree_lock (widely used, in set_page_dirty,
43 * in arch-dependent flush_dcache_mmap_lock,
44 * within inode_lock in __sync_single_inode)
48 #include <linux/pagemap.h>
49 #include <linux/swap.h>
50 #include <linux/swapops.h>
51 #include <linux/slab.h>
52 #include <linux/init.h>
53 #include <linux/rmap.h>
54 #include <linux/rcupdate.h>
55 #include <linux/module.h>
56 #include <linux/kallsyms.h>
57 #include <linux/vs_base.h>
58 #include <linux/vs_memory.h>
60 #include <asm/tlbflush.h>
62 struct kmem_cache *anon_vma_cachep;
64 static inline void validate_anon_vma(struct vm_area_struct *find_vma)
66 #ifdef CONFIG_DEBUG_VM
67 struct anon_vma *anon_vma = find_vma->anon_vma;
68 struct vm_area_struct *vma;
69 unsigned int mapcount = 0;
72 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
74 BUG_ON(mapcount > 100000);
82 /* This must be called under the mmap_sem. */
83 int anon_vma_prepare(struct vm_area_struct *vma)
85 struct anon_vma *anon_vma = vma->anon_vma;
88 if (unlikely(!anon_vma)) {
89 struct mm_struct *mm = vma->vm_mm;
90 struct anon_vma *allocated, *locked;
92 anon_vma = find_mergeable_anon_vma(vma);
96 spin_lock(&locked->lock);
98 anon_vma = anon_vma_alloc();
99 if (unlikely(!anon_vma))
101 allocated = anon_vma;
105 /* page_table_lock to protect against threads */
106 spin_lock(&mm->page_table_lock);
107 if (likely(!vma->anon_vma)) {
108 vma->anon_vma = anon_vma;
109 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
112 spin_unlock(&mm->page_table_lock);
115 spin_unlock(&locked->lock);
116 if (unlikely(allocated))
117 anon_vma_free(allocated);
122 void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next)
124 BUG_ON(vma->anon_vma != next->anon_vma);
125 list_del(&next->anon_vma_node);
128 void __anon_vma_link(struct vm_area_struct *vma)
130 struct anon_vma *anon_vma = vma->anon_vma;
133 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
134 validate_anon_vma(vma);
138 void anon_vma_link(struct vm_area_struct *vma)
140 struct anon_vma *anon_vma = vma->anon_vma;
143 spin_lock(&anon_vma->lock);
144 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
145 validate_anon_vma(vma);
146 spin_unlock(&anon_vma->lock);
150 void anon_vma_unlink(struct vm_area_struct *vma)
152 struct anon_vma *anon_vma = vma->anon_vma;
158 spin_lock(&anon_vma->lock);
159 validate_anon_vma(vma);
160 list_del(&vma->anon_vma_node);
162 /* We must garbage collect the anon_vma if it's empty */
163 empty = list_empty(&anon_vma->head);
164 spin_unlock(&anon_vma->lock);
167 anon_vma_free(anon_vma);
170 static void anon_vma_ctor(void *data, struct kmem_cache *cachep,
173 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
174 SLAB_CTOR_CONSTRUCTOR) {
175 struct anon_vma *anon_vma = data;
177 spin_lock_init(&anon_vma->lock);
178 INIT_LIST_HEAD(&anon_vma->head);
182 void __init anon_vma_init(void)
184 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
185 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL);
189 * Getting a lock on a stable anon_vma from a page off the LRU is
190 * tricky: page_lock_anon_vma rely on RCU to guard against the races.
192 static struct anon_vma *page_lock_anon_vma(struct page *page)
194 struct anon_vma *anon_vma = NULL;
195 unsigned long anon_mapping;
198 anon_mapping = (unsigned long) page->mapping;
199 if (!(anon_mapping & PAGE_MAPPING_ANON))
201 if (!page_mapped(page))
204 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
205 spin_lock(&anon_vma->lock);
212 * At what user virtual address is page expected in vma?
214 static inline unsigned long
215 vma_address(struct page *page, struct vm_area_struct *vma)
217 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
218 unsigned long address;
220 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
221 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
222 /* page should be within any vma from prio_tree_next */
223 BUG_ON(!PageAnon(page));
230 * At what user virtual address is page expected in vma? checking that the
231 * page matches the vma: currently only used on anon pages, by unuse_vma;
233 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
235 if (PageAnon(page)) {
236 if ((void *)vma->anon_vma !=
237 (void *)page->mapping - PAGE_MAPPING_ANON)
239 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
241 vma->vm_file->f_mapping != page->mapping)
245 return vma_address(page, vma);
249 * Check that @page is mapped at @address into @mm.
251 * On success returns with pte mapped and locked.
253 pte_t *page_check_address(struct page *page, struct mm_struct *mm,
254 unsigned long address, spinlock_t **ptlp)
262 pgd = pgd_offset(mm, address);
263 if (!pgd_present(*pgd))
266 pud = pud_offset(pgd, address);
267 if (!pud_present(*pud))
270 pmd = pmd_offset(pud, address);
271 if (!pmd_present(*pmd))
274 pte = pte_offset_map(pmd, address);
275 /* Make a quick check before getting the lock */
276 if (!pte_present(*pte)) {
281 ptl = pte_lockptr(mm, pmd);
283 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
287 pte_unmap_unlock(pte, ptl);
292 * Subfunctions of page_referenced: page_referenced_one called
293 * repeatedly from either page_referenced_anon or page_referenced_file.
295 static int page_referenced_one(struct page *page,
296 struct vm_area_struct *vma, unsigned int *mapcount)
298 struct mm_struct *mm = vma->vm_mm;
299 unsigned long address;
304 address = vma_address(page, vma);
305 if (address == -EFAULT)
308 pte = page_check_address(page, mm, address, &ptl);
312 if (ptep_clear_flush_young(vma, address, pte))
315 /* Pretend the page is referenced if the task has the
316 swap token and is in the middle of a page fault. */
317 if (mm != current->mm && has_swap_token(mm) &&
318 rwsem_is_locked(&mm->mmap_sem))
322 pte_unmap_unlock(pte, ptl);
327 static int page_referenced_anon(struct page *page)
329 unsigned int mapcount;
330 struct anon_vma *anon_vma;
331 struct vm_area_struct *vma;
334 anon_vma = page_lock_anon_vma(page);
338 mapcount = page_mapcount(page);
339 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
340 referenced += page_referenced_one(page, vma, &mapcount);
344 spin_unlock(&anon_vma->lock);
349 * page_referenced_file - referenced check for object-based rmap
350 * @page: the page we're checking references on.
352 * For an object-based mapped page, find all the places it is mapped and
353 * check/clear the referenced flag. This is done by following the page->mapping
354 * pointer, then walking the chain of vmas it holds. It returns the number
355 * of references it found.
357 * This function is only called from page_referenced for object-based pages.
359 static int page_referenced_file(struct page *page)
361 unsigned int mapcount;
362 struct address_space *mapping = page->mapping;
363 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
364 struct vm_area_struct *vma;
365 struct prio_tree_iter iter;
369 * The caller's checks on page->mapping and !PageAnon have made
370 * sure that this is a file page: the check for page->mapping
371 * excludes the case just before it gets set on an anon page.
373 BUG_ON(PageAnon(page));
376 * The page lock not only makes sure that page->mapping cannot
377 * suddenly be NULLified by truncation, it makes sure that the
378 * structure at mapping cannot be freed and reused yet,
379 * so we can safely take mapping->i_mmap_lock.
381 BUG_ON(!PageLocked(page));
383 spin_lock(&mapping->i_mmap_lock);
386 * i_mmap_lock does not stabilize mapcount at all, but mapcount
387 * is more likely to be accurate if we note it after spinning.
389 mapcount = page_mapcount(page);
391 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
392 if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE))
393 == (VM_LOCKED|VM_MAYSHARE)) {
397 referenced += page_referenced_one(page, vma, &mapcount);
402 spin_unlock(&mapping->i_mmap_lock);
407 * page_referenced - test if the page was referenced
408 * @page: the page to test
409 * @is_locked: caller holds lock on the page
411 * Quick test_and_clear_referenced for all mappings to a page,
412 * returns the number of ptes which referenced the page.
414 int page_referenced(struct page *page, int is_locked)
418 if (page_test_and_clear_young(page))
421 if (TestClearPageReferenced(page))
424 if (page_mapped(page) && page->mapping) {
426 referenced += page_referenced_anon(page);
428 referenced += page_referenced_file(page);
429 else if (TestSetPageLocked(page))
433 referenced += page_referenced_file(page);
440 static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
442 struct mm_struct *mm = vma->vm_mm;
443 unsigned long address;
448 address = vma_address(page, vma);
449 if (address == -EFAULT)
452 pte = page_check_address(page, mm, address, &ptl);
456 if (!pte_dirty(*pte) && !pte_write(*pte))
459 entry = ptep_get_and_clear(mm, address, pte);
460 entry = pte_mkclean(entry);
461 entry = pte_wrprotect(entry);
462 ptep_establish(vma, address, pte, entry);
463 lazy_mmu_prot_update(entry);
467 pte_unmap_unlock(pte, ptl);
472 static int page_mkclean_file(struct address_space *mapping, struct page *page)
474 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
475 struct vm_area_struct *vma;
476 struct prio_tree_iter iter;
479 BUG_ON(PageAnon(page));
481 spin_lock(&mapping->i_mmap_lock);
482 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
483 if (vma->vm_flags & VM_SHARED)
484 ret += page_mkclean_one(page, vma);
486 spin_unlock(&mapping->i_mmap_lock);
490 int page_mkclean(struct page *page)
494 WARN_ON_ONCE(!PageLocked(page));
496 if (page_mapped(page)) {
497 struct address_space *mapping = page_mapping(page);
499 ret = page_mkclean_file(mapping, page);
506 * page_set_anon_rmap - setup new anonymous rmap
507 * @page: the page to add the mapping to
508 * @vma: the vm area in which the mapping is added
509 * @address: the user virtual address mapped
511 static void __page_set_anon_rmap(struct page *page,
512 struct vm_area_struct *vma, unsigned long address)
514 struct anon_vma *anon_vma = vma->anon_vma;
517 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
518 page->mapping = (struct address_space *) anon_vma;
520 page->index = linear_page_index(vma, address);
523 * nr_mapped state can be updated without turning off
524 * interrupts because it is not modified via interrupt.
526 __inc_zone_page_state(page, NR_ANON_PAGES);
530 * page_add_anon_rmap - add pte mapping to an anonymous page
531 * @page: the page to add the mapping to
532 * @vma: the vm area in which the mapping is added
533 * @address: the user virtual address mapped
535 * The caller needs to hold the pte lock.
537 void page_add_anon_rmap(struct page *page,
538 struct vm_area_struct *vma, unsigned long address)
540 if (atomic_inc_and_test(&page->_mapcount))
541 __page_set_anon_rmap(page, vma, address);
542 /* else checking page index and mapping is racy */
546 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
547 * @page: the page to add the mapping to
548 * @vma: the vm area in which the mapping is added
549 * @address: the user virtual address mapped
551 * Same as page_add_anon_rmap but must only be called on *new* pages.
552 * This means the inc-and-test can be bypassed.
554 void page_add_new_anon_rmap(struct page *page,
555 struct vm_area_struct *vma, unsigned long address)
557 atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */
558 __page_set_anon_rmap(page, vma, address);
562 * page_add_file_rmap - add pte mapping to a file page
563 * @page: the page to add the mapping to
565 * The caller needs to hold the pte lock.
567 void page_add_file_rmap(struct page *page)
569 if (atomic_inc_and_test(&page->_mapcount))
570 __inc_zone_page_state(page, NR_FILE_MAPPED);
574 * page_remove_rmap - take down pte mapping from a page
575 * @page: page to remove mapping from
577 * The caller needs to hold the pte lock.
579 void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
581 if (atomic_add_negative(-1, &page->_mapcount)) {
582 if (unlikely(page_mapcount(page) < 0)) {
583 printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));
584 printk (KERN_EMERG " page->flags = %lx\n", page->flags);
585 printk (KERN_EMERG " page->count = %x\n", page_count(page));
586 printk (KERN_EMERG " page->mapping = %p\n", page->mapping);
588 print_symbol (KERN_EMERG " vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage);
592 * It would be tidy to reset the PageAnon mapping here,
593 * but that might overwrite a racing page_add_anon_rmap
594 * which increments mapcount after us but sets mapping
595 * before us: so leave the reset to free_hot_cold_page,
596 * and remember that it's only reliable while mapped.
597 * Leaving it set also helps swapoff to reinstate ptes
598 * faster for those pages still in swapcache.
600 if (page_test_and_clear_dirty(page))
601 set_page_dirty(page);
602 __dec_zone_page_state(page,
603 PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
608 * Subfunctions of try_to_unmap: try_to_unmap_one called
609 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
611 static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
614 struct mm_struct *mm = vma->vm_mm;
615 unsigned long address;
619 int ret = SWAP_AGAIN;
621 address = vma_address(page, vma);
622 if (address == -EFAULT)
625 pte = page_check_address(page, mm, address, &ptl);
630 * If the page is mlock()d, we cannot swap it out.
631 * If it's recently referenced (perhaps page_referenced
632 * skipped over this mm) then we should reactivate it.
634 if (!migration && ((vma->vm_flags & VM_LOCKED) ||
635 (ptep_clear_flush_young(vma, address, pte)))) {
640 /* Nuke the page table entry. */
641 flush_cache_page(vma, address, page_to_pfn(page));
642 pteval = ptep_clear_flush(vma, address, pte);
644 /* Move the dirty bit to the physical page now the pte is gone. */
645 if (pte_dirty(pteval))
646 set_page_dirty(page);
648 /* Update high watermark before we lower rss */
649 update_hiwater_rss(mm);
651 if (PageAnon(page)) {
652 swp_entry_t entry = { .val = page_private(page) };
654 if (PageSwapCache(page)) {
656 * Store the swap location in the pte.
657 * See handle_pte_fault() ...
659 swap_duplicate(entry);
660 if (list_empty(&mm->mmlist)) {
661 spin_lock(&mmlist_lock);
662 if (list_empty(&mm->mmlist))
663 list_add(&mm->mmlist, &init_mm.mmlist);
664 spin_unlock(&mmlist_lock);
666 dec_mm_counter(mm, anon_rss);
667 #ifdef CONFIG_MIGRATION
670 * Store the pfn of the page in a special migration
671 * pte. do_swap_page() will wait until the migration
672 * pte is removed and then restart fault handling.
675 entry = make_migration_entry(page, pte_write(pteval));
678 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
679 BUG_ON(pte_file(*pte));
681 #ifdef CONFIG_MIGRATION
683 /* Establish migration entry for a file page */
685 entry = make_migration_entry(page, pte_write(pteval));
686 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
689 dec_mm_counter(mm, file_rss);
692 page_remove_rmap(page, vma);
693 page_cache_release(page);
696 pte_unmap_unlock(pte, ptl);
702 * objrmap doesn't work for nonlinear VMAs because the assumption that
703 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
704 * Consequently, given a particular page and its ->index, we cannot locate the
705 * ptes which are mapping that page without an exhaustive linear search.
707 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
708 * maps the file to which the target page belongs. The ->vm_private_data field
709 * holds the current cursor into that scan. Successive searches will circulate
710 * around the vma's virtual address space.
712 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
713 * more scanning pressure is placed against them as well. Eventually pages
714 * will become fully unmapped and are eligible for eviction.
716 * For very sparsely populated VMAs this is a little inefficient - chances are
717 * there there won't be many ptes located within the scan cluster. In this case
718 * maybe we could scan further - to the end of the pte page, perhaps.
720 #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
721 #define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
723 static void try_to_unmap_cluster(unsigned long cursor,
724 unsigned int *mapcount, struct vm_area_struct *vma)
726 struct mm_struct *mm = vma->vm_mm;
734 unsigned long address;
737 address = (vma->vm_start + cursor) & CLUSTER_MASK;
738 end = address + CLUSTER_SIZE;
739 if (address < vma->vm_start)
740 address = vma->vm_start;
741 if (end > vma->vm_end)
744 pgd = pgd_offset(mm, address);
745 if (!pgd_present(*pgd))
748 pud = pud_offset(pgd, address);
749 if (!pud_present(*pud))
752 pmd = pmd_offset(pud, address);
753 if (!pmd_present(*pmd))
756 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
758 /* Update high watermark before we lower rss */
759 update_hiwater_rss(mm);
761 for (; address < end; pte++, address += PAGE_SIZE) {
762 if (!pte_present(*pte))
764 page = vm_normal_page(vma, address, *pte);
765 BUG_ON(!page || PageAnon(page));
767 if (ptep_clear_flush_young(vma, address, pte))
770 /* Nuke the page table entry. */
771 flush_cache_page(vma, address, pte_pfn(*pte));
772 pteval = ptep_clear_flush(vma, address, pte);
774 /* If nonlinear, store the file page offset in the pte. */
775 if (page->index != linear_page_index(vma, address))
776 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
778 /* Move the dirty bit to the physical page now the pte is gone. */
779 if (pte_dirty(pteval))
780 set_page_dirty(page);
782 page_remove_rmap(page, vma);
783 page_cache_release(page);
784 dec_mm_counter(mm, file_rss);
787 pte_unmap_unlock(pte - 1, ptl);
790 static int try_to_unmap_anon(struct page *page, int migration)
792 struct anon_vma *anon_vma;
793 struct vm_area_struct *vma;
794 int ret = SWAP_AGAIN;
796 anon_vma = page_lock_anon_vma(page);
800 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
801 ret = try_to_unmap_one(page, vma, migration);
802 if (ret == SWAP_FAIL || !page_mapped(page))
805 spin_unlock(&anon_vma->lock);
810 * try_to_unmap_file - unmap file page using the object-based rmap method
811 * @page: the page to unmap
813 * Find all the mappings of a page using the mapping pointer and the vma chains
814 * contained in the address_space struct it points to.
816 * This function is only called from try_to_unmap for object-based pages.
818 static int try_to_unmap_file(struct page *page, int migration)
820 struct address_space *mapping = page->mapping;
821 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
822 struct vm_area_struct *vma;
823 struct prio_tree_iter iter;
824 int ret = SWAP_AGAIN;
825 unsigned long cursor;
826 unsigned long max_nl_cursor = 0;
827 unsigned long max_nl_size = 0;
828 unsigned int mapcount;
830 spin_lock(&mapping->i_mmap_lock);
831 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
832 ret = try_to_unmap_one(page, vma, migration);
833 if (ret == SWAP_FAIL || !page_mapped(page))
837 if (list_empty(&mapping->i_mmap_nonlinear))
840 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
841 shared.vm_set.list) {
842 if ((vma->vm_flags & VM_LOCKED) && !migration)
844 cursor = (unsigned long) vma->vm_private_data;
845 if (cursor > max_nl_cursor)
846 max_nl_cursor = cursor;
847 cursor = vma->vm_end - vma->vm_start;
848 if (cursor > max_nl_size)
849 max_nl_size = cursor;
852 if (max_nl_size == 0) { /* any nonlinears locked or reserved */
858 * We don't try to search for this page in the nonlinear vmas,
859 * and page_referenced wouldn't have found it anyway. Instead
860 * just walk the nonlinear vmas trying to age and unmap some.
861 * The mapcount of the page we came in with is irrelevant,
862 * but even so use it as a guide to how hard we should try?
864 mapcount = page_mapcount(page);
867 cond_resched_lock(&mapping->i_mmap_lock);
869 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
870 if (max_nl_cursor == 0)
871 max_nl_cursor = CLUSTER_SIZE;
874 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
875 shared.vm_set.list) {
876 if ((vma->vm_flags & VM_LOCKED) && !migration)
878 cursor = (unsigned long) vma->vm_private_data;
879 while ( cursor < max_nl_cursor &&
880 cursor < vma->vm_end - vma->vm_start) {
881 try_to_unmap_cluster(cursor, &mapcount, vma);
882 cursor += CLUSTER_SIZE;
883 vma->vm_private_data = (void *) cursor;
884 if ((int)mapcount <= 0)
887 vma->vm_private_data = (void *) max_nl_cursor;
889 cond_resched_lock(&mapping->i_mmap_lock);
890 max_nl_cursor += CLUSTER_SIZE;
891 } while (max_nl_cursor <= max_nl_size);
894 * Don't loop forever (perhaps all the remaining pages are
895 * in locked vmas). Reset cursor on all unreserved nonlinear
896 * vmas, now forgetting on which ones it had fallen behind.
898 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
899 vma->vm_private_data = NULL;
901 spin_unlock(&mapping->i_mmap_lock);
906 * try_to_unmap - try to remove all page table mappings to a page
907 * @page: the page to get unmapped
909 * Tries to remove all the page table entries which are mapping this
910 * page, used in the pageout path. Caller must hold the page lock.
913 * SWAP_SUCCESS - we succeeded in removing all mappings
914 * SWAP_AGAIN - we missed a mapping, try again later
915 * SWAP_FAIL - the page is unswappable
917 int try_to_unmap(struct page *page, int migration)
921 BUG_ON(!PageLocked(page));
924 ret = try_to_unmap_anon(page, migration);
926 ret = try_to_unmap_file(page, migration);
928 if (!page_mapped(page))